Motion Necessary to Achieve Mallet Internal Rotation Positions in Children With Brachial Plexus Birth Palsy
Stephanie A Russo1, Scott H Kozin2,3, Dan A Zlotolow2,3
1Department of Orthopaedic Surgery, UPMC Hamot, Erie.
Insights
Children with brachial plexus birth palsy (BPBP) struggle with the hand-to-spine test. The hand-to-belly test, assessing internal rotation, is a more reliable measure for some children with BPBP.
Area of Science:
- Pediatric Orthopedics
- Biomechanics
- Rehabilitation Medicine
Background:
- Brachial plexus birth palsy (BPBP) affects upper extremity function in children.
- Clinical assessments like the Mallet classification evaluate shoulder internal rotation using hand-to-spine or hand-to-belly positions.
- Children with BPBP often find the hand-to-spine task challenging.
Purpose of the Study:
- To compare scapulothoracic and glenohumeral (GH) parameters related to successful completion of hand-to-spine and hand-to-belly tasks in children with BPBP.
- To identify biomechanical differences underlying performance in modified Mallet classification positions.
Main Methods:
- Motion capture technology was used to analyze the movements of 32 children with BPBP.
- Measurements were taken in hand-on-spine, hand-to-belly (internal rotation), hand-to-mouth, and maximal humerothoracic extension positions.
- Modified Mallet scores were assigned by a pediatric hand surgeon.
Main Results:
- Better hand-to-spine performance correlated with significantly greater GH extension and a trend towards increased GH internal rotation.
- Improved hand-to-belly performance was associated with significantly greater GH internal rotation, but not GH extension.
- A moderate correlation was found between hand-on-spine and hand-to-belly scores, yet 54% of children mastered hand-to-belly but not hand-to-spine.
Conclusions:
- Successful hand-to-spine movement requires a multiplanar motion involving both shoulder internal rotation and extension.
- The hand-to-belly task is less dependent on extension and serves as a more suitable assessment for internal rotation, especially for children undergoing interventions impacting shoulder mobility.
Background:
Upper extremity function in children with brachial plexus birth palsy (BPBP) is assessed with clinical tests such as the Mallet classification, which uses a hand to spine position to assess shoulder internal rotation, or the modified Mallet classification, which adds an additional internal rotation task (hand to belly). Children with BPBP frequently have difficulty performing the hand to spine task. This study compared scapulothoracic and glenohumeral (GH) parameters associated with successful completion of the hand to spine and hand to belly modified Mallet positions.
Methods:
Motion capture measurement of 32 children with BPBP was performed in hand on spine, internal rotation (hand to belly), hand to mouth, and maximal humerothoracic extension positions. Modified Mallet scores were determined by a hand surgeon.
Results:
Children with better hand to spine performance demonstrated significantly greater GH extension and a nonsignificant trend toward increased GH internal rotation compared with children with scores <3. Children with better internal rotation position performance demonstrated significantly greater GH internal rotation and no significant difference in GH extension. Hand on spine and internal rotation Mallet scores moderately correlated (Pearson r=0.469); however, 54% of children who could place their palms flat on their bellies could not reach behind their backs.
Conclusions:
Successfully reaching behind one's back requires both internal rotation and extension, representing a multiplanar motion. The hand to belly performance is less affected by extension and should be considered for internal rotation assessment, particularly for children undergoing surgical intervention that may affect internal rotation.
Level Of Evidence:
Level II.
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